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61.
Silicon - Silicon carbide piezoresistive pressure sensor is more suitable for harsh environment due to its wide bandgap, corrosion tolerance, excellent chemical inertness, high Young’s... 相似文献
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This paper presents two novel six-axis magnetic-levitation (maglev) stages capable of nanoscale positioning. These stages have very simple and compact structures, which is advantageous to meet the demanding positioning requirements of next-generation nanomanipulation and nanomanufacturing. Six-axis motion generation is accomplished by the minimum number of actuators and sensors. The first-generation maglev stage, namely the Δ-stage, is capable of generating translation of 300 μm and demonstrates position resolution better than 2 nm root-mean-square (rms). The second-generation maglev stage, namely the Y-stage, is capable of positioning at a resolution better than 3 nm rms over a planar travel range of 5 mm × 5 mm. A novel actuation scheme was developed for the compact structure of this stage that enables six-axis force generation with just three permanent-magnet pieces. This paper focuses on the design and precision construction of the actuator units, the moving platens, and the stationary base plates. The performance of the two precision positioners is compared in terms of their positioning and load-carrying capabilities and ease of manufacture. Control system design for the two positioners is discussed and an experimental plant transfer function model is presented for the Y-stage. The superiority of the developed instruments is also demonstrated over other prevailing precision positioning systems in terms of the travel range, resolution, and dynamic range. The potential applications of the maglev positioners include semiconductor manufacturing, microfabrication and assembly, nanoscale profiling, and nanoindentation. 相似文献
63.
Carbon dioxide emission and its regulation at land–water interface downstream of a point source at Ganga River (India)
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Deepa Jaiswal Ekabal Siddiqui Kavita Verma Jitendra Pandey 《Water and Environment Journal》2018,32(3):351-357
The streams and rivers are considered hotspots of CO2 exchange; and representative direct CO2 emission measurements are essential for a correct regional estimate. We measured CO2 emission flux at 15 sites at land–water interface downstream of a point source during low flow for three consecutive months for the year 2017. The general range of CO2 efflux observed here was close to the results of regional studies, although values near the point source were disproportionately high (>350 mg/m2/h). CO2 emission flux showed strong dependence on total organic carbon (TOC; R2 = 0.96; P < 0.001), (R2 = 0.88; P < 0.001), soluble reactive‐P (SRP; R2 = 0.91; P < 0.001) and microbial activity measured in terms of fluorescein diacetate activity (FDAase; R2 = 0.92; P < 0.001) and substrate induced respiration (SIR; R2 = 0.96; P < 0.001). Because point source‐associated interfaces provide heterogeneous habitats, our study suggests the need for large scale monitoring of CO2 emission at land–water interface of major rivers for more correctly presenting the regional scale CO2 budget. 相似文献
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European Journal of Wood and Wood Products - Im vorigen Teilbericht wurden Untersuchungen über Amylase von zwei Pilzen beschrieben. Der vorliegende Bericht befaßt sich mit Cellulase und... 相似文献
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Jaspal Singh Sanjeev Kumar N. K. Verma 《Journal of Materials Science: Materials in Electronics》2014,25(5):2267-2272
Cd1?xNixSe (x = 0.0, 0.02, 0.05 and 0.1) nanoparticles have been synthesized by chemical route. X-ray diffraction analysis shows crystalline nature of synthesized nanoparticles possessing wurtzite phase having hexagonal structure. Transmission electron microscopy depicts spherical morphology and uniform particle size distribution of pure and Ni-doped CdSe nanoparticles. The blue-shift in band gap has been observed with Ni-doping concentration. Photoluminescence study shows the presence of intrinsic defects (VCd–VSe) in the synthesized nanoparticles. Electron spin resonance (ESR) analysis reveals the long range ferromagnetic ordering in pure and doped nanoparticles. ESR study also indicates that Ni ions exist in +2 oxidation state in host nanoparticles. The magnetic hysteresis (M-H) loops display ferromagnetism at room temperature in pure and Ni-doped CdSe nanoparticles. The increase of ferromagnetic behavior has been observed with Ni-doping concentration. M-H analyses indicate that defects and carrier mediated exchange interactions are responsible for ferromagnetic ordering, in the present study. 相似文献
68.
Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping was carried out. The influence of equilibration time, equilibrium pH and extractant concentration on the extraction of both the metals was studied. It was found that the copper extraction equilibrium was reached in a shorter time than the nickel extraction equilibrium. Nickel extraction decreases above an equilibrium pH of 9.0, while the extraction of copper remains unaffected by the changes in the equilibrium pH range of 7–10. Co-extraction, ammonia scrubbing and the selective stripping of copper and nickel were performed for a solution containing 3 g/l each of copper and nickel and 60 g/l ammonium carbonate. The extraction and the percentage stripping of copper and nickel were almost quantitative. 相似文献
69.
A three-lobe journal bearing is analytically investigated to determine its dynamic performance when three main parameters, i.e. turbulence, load orientation, and rotor flexibility are varied. Reynolds numbers up to 12000, rotor dimensionless flexibilities up to 4, and load orientations up to 30 degrees on either side of the vertical load line are considered. Thus, almost all cases of practical interest are studied. The stability of a three-lobe bearing improves due to turbulence at high Sommerfeld numbers (more than 0.6) for a rigid rotor, while it is virtually the same for flexible rotors. Conversely, the load orientation has a pronounced effect on stability for both rigid and flexible rotors. 相似文献
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